How did the arrival of european colonists in north america influence interactions between different groups of americans during the mid 17th century?
a) it allowed western tribes to migrate in huge numbers to eastern tribes' territories.
b) it created conflicts between tribes over resources that were traded to europeans.
c) it led tribes to isolate themselves from one another to prevent the spread of disease.
d) it resulted in most tribes uniting in military campaigns against european colonists.